In a mixing bowl, whisk together the eggs and sugar until smooth and slightly pale.

In a saucepan, combine the milk and heavy cream over medium heat; stir occasionally until warm but not boiling.

Slowly pour the warm milk mixture into the egg and sugar mixture while whisking constantly.

Pour the combined mixture back into the saucepan and cook over low heat, stirring constantly until it thickens slightly and coats the back of a spoon, about 5 minutes.

Remove from heat and stir in vanilla extract and ground nutmeg.

Let the egg nog cool to room temperature, then refrigerate for at least 2 hours.

Once chilled, stir and pour into glasses. Garnish with a sprinkle of nutmeg or cinnamon.

Add bourbon or rum if desired and enjoy responsibly.